Best online mathematics videos? I know of two good mathematics videos available online, namely:

*

*Sphere inside out (part I and  part II)

*Moebius transformation revealed
Do you know of any other good math videos? Share.
 A: My personal favorite in Dimensions, that was mentioned before by Gerald Edgar. For a neat and clear exposition the Geom.of 3 manifolds, Poincaré conjecture, etc I recommend this lecture by C.McMullen. Or Das Schöne denken (hosted at the HIM in Bonn), for a good "glimpse in the world of the mathematician". Jos Leys' mathematical imagery contains some (interesting) videos and (a lot of beautiful) images. 
A: There are Stephen Boyd's lecture videos on convex optimization:
http://www.stanford.edu/class/ee364a/videos.html
A: I guess all of John Conway's lectures are great. Some of those can be found here :
http://www.math.princeton.edu/facultypapers/Conway/
A: 77 instructional videos on category theory:
https://www.youtube.com/TheCatsters
I know you said "only one video per post", but I'm not posting 77 times...
A: The series of videos from IAS School of Mathematics
A: The IHES also has a lot of on-line videos. In particular, I like very much the ones from the "Colloque Grothendieck". 
A: Dror Bar-Natan has begin putting many of his lectures and talks online in video format. I'm not claiming that these are the 'best' online maths videos, but they're certainly interesting, and in particular he's come up with some neat tricks to associate publicly editable annotations with particular moments in the video.
A: Not lecture videos or anything, but the stuff from Oliver Labs is very good for just illustrating geometric stuff, like blowups and dual curves.
A: I am surprised that nobody mentioned the four-week workshop at Göttingen on arithmetic geometry in 2006 summer. Almost all of the videos are still available. Wonderful videos.
A: Videos recorded at IMPA:
http://video.impa.br/index.php?page=download
(some in English, some in Portuguese)
A: Stoney Brook math videos:
http://www.math.sunysb.edu/Videos/dfest/
http://www.math.sunysb.edu/html/videos.shtml
A: This is an old thread, but this video was recently posted to the Don Davis topology list, and I have to share it. It was created by Niles Johnson at UGA and it illustrates the Hopf fibration.
http://www.youtube.com/watch?v=AKotMPGFJYk
A: This one is quite old but it was fun when I watched a few years ago.
It's about Fermat's Last theorem.
http://www.archive.org/details/fermats_last_theorem
A: Lots of Lie Theory talks:
http://sms.cam.ac.uk/collection/533438?mediaOffset=20&mediaMax=20&mediaOrder=asc&mediaSort=title#Media
A: This isn't purely a math video, it's an interview with Peter Woit and it is something of a summary of the main issues discussed on his blog and in his book.  He talks about math vs. physics culture, especially the string theory community.
edit: the link appears to have changed.
https://bigthink.com/u/peterwoit
Discussion here:
http://www.math.columbia.edu/~woit/wordpress/?p=2670
A: John Stillwell - ET Math: How different could it be? A nice talk given at the SETI Institute.
A: I have compiled a list (1500+) of math videos at http://pinterest.com/mathematicsprof/ .   If anyone is aware of others, please send them to me. 
A: Most of the talks at MSRI are videotaped and placed on the web here:
http://www.msri.org/communications/vmath/index_html
A: The "Touching Soap Films" series by Springer. about minimal surfaces. Some excerpts of the video are available here:
http://page.mi.fu-berlin.de/polthier/video/Touching/Scenes.html
A: This video is less about mathematics, but about a fascinating mathematician in two bodies who helped saving medieval unicorns - students liked it.  
A: My good friend  Professor Elvis Zap  has the "Calculus Rap," the "Quantum Gravity Topological Quantum Field Theory Blues," a vid on constructing "Boy's Surface," "Drawing the hypercube (yes he knows there is a line missing in part 1)," A few things on quandles, and a bunch of precalculus and calculus videos. In order to embarrass all involved, he posted the series "Dehn's Dilemma" that was recorded  in Italy last summer.
A: Elvis's youtube link 
A: On this page of sample animations using the k3d program there's a short animation of a "flower" blooming which is actually the first part of the sphere eversion.
A: For a course on cluster algebras (by S. Fomin): http://qgm.au.dk/video/mc/cluster/
EDIT: Some graduate short-courses in FCEyN, UBA, Buenos Aires, Argentina:


*

*J. Harris, Intersection Theory

*R. Hartshorne, Introduction to Deformation Theory

*D. Maclagan, Introduction to Tropical Algebraic Geometry

*P. Beelen, Algebraic Geometric Codes


Here are the links to the videos of these 4 lectures.
A: My personal all-time favorite is the Klein Four with their song "Finite Simple Group (of Order Two)"... it has lots of puns on topology in it, but I guess it doesn't teach anything.
Here's the link to the "Finite Simple Group" song
A: I believe this was mentioned elsewhere, but for completeness, here's Serre on writing.
A: Dimensions
Möbius Transformations Revealed
A: Among the best math videos can be found here:
http://www.khanacademy.org/
(or the youtube-channel: http://www.youtube.com/khanacademy )
There is everything from counting to solving differential equations with Laplace transforms - nearly 1.000 videos altogether (and the guy is funny :-)
A: Sir Michael Atiyah: Beauty in Mathematics.
A: Ken Ribet's introductory lecture on Serre's modularity conjecture. Useful and quite easy to follow and understand. http://fora.tv/2007/10/25/Kenneth_Ribet_Serre_s_Modularity_Conjecture
A: NMU(https://en.wikipedia.org/wiki/Independent_University_of_Moscow) and MIAN lectures 2009-2010 (in Russian)
http://erb-files.narod.ru/
A: Hitler learns topology
A: Timothy Gowers' "The Importance of Mathematics" never fails to instill a sense of purpose in my work, even when I feel I'm doing "useless" mathematics.
A: Richard Feynman gave the 1964 Messenger Lectures at Cornell University --- this is an endowed lecture series to which a number of famous scholars have been invited, including several physicists.  His lectures were recorded, and Bill Gates bought the rights to them and has provided them to the public for free.
http://research.microsoft.com/apps/tools/tuva/index.html
The content is mostly designed for a general audience, so if you have never learned physics you will learn something.  And if you have studied plenty of physics already, you will be pleased to see the master at work in his prime.  I very much enjoyed watching it.
A: This video about Andrew Wiles and the proof of Fermat's Last Theorem is the only time I've seen the real excitement of mathematics presented accurately.  
A: 'Not Knot' is also a nice vid
http://www.youtube.com/watch?v=AGLPbSMxSUM
A: The Newton institute in Cambridge tapes alot (all?) of it's lectures, and they can be found on the Institutes webpage. High quality for videos of lectures.
A: At the accessible end of the scale, Vi Hart's "doodling in math class" series and subsequent videos are a delight. 
A: An excellent (and very lively) overview of basic one-variable calculus: Calculus I in 20 minutes: Part I, Part II.
A: The  Abdus Salam International Centre for Theoretical Physics has lots of lectures in mathematics and physics.Some of them are difficult to find in other places(Complex Analysis,Abstract Algebra,Topology,Functional Analysis,Algebraic Geometry..).For the same topic(ex:Complex Analysis)there are lectures by 2 ore more lecturers so you can choose.
http://www.ictp.it/
http://www.ictp.tv/diploma/index07-08.php?activityid=MTH
http://www.ictp.tv/diploma/index08-09.php?activityid=MTH
A: A nice introduction to representation theory of compact lie groups, sl2(R) and other topics:
http://www.math.utah.edu/vigre/minicourses/sl2/schedule.html
A: A few talks under the heading "What is ..." (",,," could be "Morse Theory", for example)
given at the Freie Universität Berlin can be found here:
http://www.scivee.tv/user/5216
A: I found the Graduate weekend repository of lectures at the Mathematics Department of Duke's University very entertaining. There is more in the other folders(G.Tian, Langlands, just to name a few   )$\ldots$
A: The complete introductory course on Algebraic Geometry by Miles Reid is very interesting (28 lectures following and extending his own undergraduate book on the subject), and his other set of lectures on Algebraic Surfaces.
A: David Cox's lectures in toric varieties at MSRI
Something really good to end the evening with :)
A: Marcus du-Sautoy's lecture - Music of The Prime Numbers, is a very nice popular talk about prime numbers
A: At the time of writing, Rutgers experimental mathematics seminar has over 200 videos up on youtube. I wish more seminars would do this!
A: I am quite surprised to see Dan Freed's lecture of Hodge Conjecture has not been mentioned. (Although it is an old thread I believe this should be in here. Before there was a QuickTime video but I am grateful to find that it has been youtubed.) 
A: As of today, the digitized tapes of CBMS Lectures on Probability Theory and Combinatorial by Michael Steele are online. I heartily recommend them — the style is informal, but educating: there are jokes, juggling lessons, speculations about the stock market, and all of these amidst beautiful mathematics.
A: Two  recent videotaped lectures by Doron Zeilberger.
The Joy of Dreaming to be Famous (Videotaped lecture), March 1,2012 
The Rise and Fall of Astrology and the Future Fall of the so-called Infinity (Videotaped lecture) March 29, 2012
A: The first Minerva Lecture by Jean-Pierre Serre at Princeton in Fall 2012 is online. There were two other lectures, and they did videotape them, but I can't find them online.
A: Any video on  
Jos Leys "Mathematical Imagery"
is a true masterpiece, and has a non-trivial mathematical content...
A: MIT's OpenCourseWare has a few math courses up:
http://ocw.mit.edu/OcwWeb/web/courses/av/index.htm#Mathematics
A: The Institute for Advanced Study tapes some of its lectures. They tend to be very good.
A: GRASP is a new lecture series at the University of Texas at Austin, which is aimed at bringing some of the fundamental concepts and big picture of the GRASP areas (Geometry, Representation, and Some Physics) to a wider audience (the intended target audience are beginning graduate students).
http://www.ma.utexas.edu/users/benzvi/GRASP.html
A: You probably won't learn much actual math from it, but One Geometry is funnier and catchier than a Snoop Dogg parody about 3-manifolds has any right to be.
A: Along the sphere eversion lines, there is also the energy-minimizing sphere eversion constructed by Rob Kusner.  I think there is a video of it at https://www.youtube.com/watch?v=I6cgca4Mmcc, though it isn't labelled as such.
Rob also has written a paper about the history of the minimax eversion.
A: I'd like to think that my math art is awesome, and start here. 
the mapping behind that video is $(x,y,z)\rightarrow(2*cos(z-y),2*sin(x-z),7*cos(y-x))$, and has a singular Jacobian -- the immediate ramification of which is that there is overlap in the video.
A: http://www.youtube.com/watch?v=VdPrCWr9Ruk&feature=player_embedded#!
is a video made by a student in the school of arichitecture using pov-ray 
is about algebraic surfaces and how they "deform"
there are a few more animations at the following url
http://www.formulas.it/animazioni.php 
they are part of on-going project about the visualization 
of mathematics (being developed by group of mathematicians and architects)  
A: Some talks on history by some leading mathematicians (mostly in French):
http://www.archivesaudiovisuelles.fr/FR/_LibraryThemas.asp?thema=541
A: Searching for a video relating to another question, I found this:
My Calculus Project
A: Documentary about infinite and its implications in mathematics (BBC)
http://www.youtube.com/watch?v=Cw-zNRNcF90
As usual, Gregory Chaitin on the history of logic
http://www.youtube.com/watch?v=HLPO-RTFU2o
Another one about logic and artificial intelligence
http://www.youtube.com/watch?v=nA3m9jgMp3U
A: All the talks of Atiyah 80+
A: http://www.youtube.com/user/njwildberger
Excellent lectures by Norman Wildberger on topics including: Geometry, Algebraic Topology, Linear Algebra, Foundations of Mathematics, and history of Mathematics
A: The famous proof of the snake lemma in the 1980's movie It's my turn (can be found on utube). 
A: 'Selmer Ranks of Elliptic Curves in Families of Quadratic Twists' by Karl Rubin
http://research.microsoft.com/apps/video/default.aspx?id=140581
A: The Dot and the Line: A Romance in Lower Mathematics
A: The University of New South Wales in Sydney has an eLearning channel on YouTube that contains lectures on a number of topics, including Algebraic Topology, Calculus, and Linear Algebra. Some computing and engineering topics are covered as well.
http://www.youtube.com/user/UNSWelearning#p/p
A: I am surprised no one has mentioned that the Kavli Institute for Theoretical Physics, the Simons Center for Geometry and Physics, and the Perimeter Institute often tape conferences.
A: I am not sure if this will qualify as math exactly, but it's amazing nonetheless. It is a film with Richard Feynman called "Feynman: Take the wold from another point of view". Here is part 1
Feynman: Take the wold from another point ov view - Part 1/4
A: I make some maths videos at home,Here is an English video:Visible Fibre Bundle 
maybe that can help some begginners.
All my maths vedios at my blog here,thirty courses of communtative algebra and I prepare to make much more in the future,but as you seen,most of them are Chinese(中文）,because I can not say much English.
A: The amazing patterns that turn up in piece-wise isometries, like circles dancing in a rhomb:
http://vimeo.com/23772888
A: They filmed the FRG Conference on Topology and Field Theories and put the lectures on youtube.
A: So much maths video in http://nptel.ac.in/ National Programme on Technology Enhanced Learning
A: I know of some youtube channels with good content. The last two link are not strictly pure math, but still worth a look.
Institut Henri Poincaré:
https://www.youtube.com/channel/UCrKGv5WY5ryaIXEmnxKVxOQ
princetonmathematics
https://www.youtube.com/channel/UCVKtRsfK1QPyHRP2QupyddQ
Institut des Hautes Études Scientifiques (IHÉS)
https://www.youtube.com/channel/UC4R1IsRVKs_qlWKTm9pT82Q
StanfordCSTheory:
https://www.youtube.com/channel/UCdZlxxfpEzQWwMvjVQ7gOJw
Simons Institute:
https://www.youtube.com/channel/UCW1C2xOfXsIzPgjXyuhkw9g
A: Discrete Integrable Systems at Isaac Newton Institute for Mathematical Sciences
A: I feel that I have something new to add.  I sometimes make mathematical videos, and I should make more.  Here is one about a 3D diagram that I made of the happy family, in group theory.  There are a lot of other videos on my channel, however, not pertaining to mathematics such as singing and art, but I hope that in the future I will make more mathematical content.
https://www.youtube.com/watch?v=_4IjnIcECoQ&t=11s
A: The video that I am adding here is a new upload in Youtube.
Here is the link: https://www.youtube.com/watch?v=aUl28Pjz89M
I have seen many videos on 21-card trick and also read many blogs on it. A very few of them has attempted to explain why this trick works. The ones give the proof, is pretty involved and requires some inclination towards the subject to understand this. But, this video has taken a totally different approach to explain the trick and why it works in a visual way. The approach is easy to understand for anyone. This is a great way of helping students get attracted towards Mathematics.
